Process for converting petroleum oil



Dec. 29, 1931. c. P. DUBBS PROCESS FOR CONVERTING PETROLEUM OIL Filed Jul-y 31, I922 li n 1| I Q In 7/572 fur.- Carbon Dubbs.

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Patented Dec. 29, 1931 UNITED STATES PATENT OFFICE CARBON r; mm, or mums. ILLINOIS. ABBIGNOB To UNIVERSAL on. rnonucrs COMPANY, or cnrcaeo, mmNoIs, A CORPORATION or sourn :oaxora rnoonss non CONVERTING rn'rnonnum on. 7

Application filed July 81,

. elevational view of the apparatus.

In a normal operation 0 the plant the raw oil is supplied from any suitable source from line 1 to pump 2 and then through line 3 Into the dephlegmator-through manifold 4 or 5, or through both and then passes down through the leg of the dephlegmator and through line 24 to cracking coils 7, positioned in any suitable furnace. The oil after being raised to a cracking temperature, is discharged into the expansion chamber 8. The liquid portion from the expansion or vaporizing chamber is drawn oil through line 9, controlled by valve 10 which directs it thence to storage. The vapors generated pass through vapor line 11 into the bottom section of the dephlegmator and as they pass up through the dephlegmator more or less of the heavier ends are condensed by coming in contact with cold oil being fed into the dephelgmator and by gradually dropping to the bottom-of the dephlegmator they flow through the dephlegmator leg through lines 6 and 24 to the cooler 25 and heating coil 7 respectively. The remaining vapors pass out through line 12 and are condensed and cooled in condensing coil 13 and pass through line 14 to receiving tank 15, which is equipped with a pressure gauge 16 and a liquid level gauge 16a.

The distillates are drawn ofi' through line 17 controlled by valve 18, while the incondensable gas is drawn off through line 19, controlled by valve 20. In this line is positioned pressure relief valve 21.

On the expansion chamber are manhole covers by which the chamber. may be readily cleaned.

In the distilling of oil in this apparatus, whether for purely fractionating or for cracking higher into lower boiling points and fractionating, it will be seen that the oil re- 1922. Serial No. 578,706.

ceives its heat treatment as it flows through coil 7 and is then discharged into the expansion chamber 8, and as it flows through this chamber the liquids are separated from the vapors, the liquids passing oil through line 9, controlled by valve 10, while the vapors pass through. line 11 into the bottom of the dephlegmator. As they pass up through-the dephlegmator they come in contactwith cool oil being fed thereinto which causes more or less of the higher boilin' point vapors to be condensed and returne to the heating or cracking coils through line 24. The remaining vapors pass through line 12, and'throu h condenser into receiver tank'15, as does a o any incondensable gas produced. The pressure on the apparatus is controlled by escape of gas regulated through valve 20 and control of drawing liquid therefrom, by regulating valve 18.

Inside of this dephlegmator are pans 22, the larger pans being practically the same size in diameter as the internal diameter of the dephlegmator, there being an opening in the center for the vapors to pass through. The edges of these pans have sufficient height to prevent the liquid from overflowing and are perforated to divide the liquid into several small streams as it percolates down through the dephlegmator. Immediately over each of these pans is a smaller pan with a lip turned on the edge so that the oil will not run over, and perforated so that the oil cooled therein will run in small streams into the pan below it. These pans of'difi'erent size are alternately placed throughout the dephlegmator.

In the normal, operation when cool reflux is not recycled through the dephlegmator, the raw oil being fed into the dephlegmator will condense only a given quantity of vapors; therefore the vapors generated in the coil 7 and expansion chamber 8 should not contain larger quantities of the higher boiling fractions, to be condensed and reheated, than the oil fed into the dephlegmator will condense.

In my process when an increased volume of heat is to be subtracted from the vapors as they pass through the dephlegmator, additional cold oil may be fed into the dephlegmator by taking out oil from the leg of the dephlegmator through line 6 passing it through reflux cooler 25 and line 26 to pump 27 thence through line 28 and valve 29 to the manifold 4 into the dephlegmator.

When treating oilhaving a wide range of boiling points in this manner, the oil is heat ed up as it flows down through the dephlegmator and more or less of the raw oil is converted into va ors which pass out of the dephlegmator into the distillate receiving tank instead of passing as liquid to the cracking coils 7. To overcome this difficulty it has been found that the length of time it takes.

to heat this oil up is governed by the distance it has to travel through these hot vapors and the shorter the distance, the less raw oil is evaporated.

There are no fixed rules governing the proper dephlegmating treatment for different oils, as each act differently, but it can be readily ascertained for any particular cut of oil by a few tests in which the oil has different distances to travel. Should the raw oil being used contain lighter cuts in considerable amounts. that would be evaporated from the heat of the vapors in the dephlegmator, then it is desirable to charge the raw oil by the pump 2 through line 3 through manifold 5 and discharge it into the top part of the dephlegmator into pan 30 and after passing through a sutlicient number of pans to preheat it but maintain its temperature below a point where an excessive amount vaporizes, the incoming raw oil together with the vapors condensed, are collected in the funnel shaped pan 31, and are drained through line 32 to the bottom part of the dephlegmator leg. The vapors condensed in the lower part of the dephlegmator which have higher boiling points are withdrawn through line 6 which is above lower extremity of the discharge from pan 31. The reflux from the cooler 25 is passed through line26 and pump 27 and discharged through line 28 to manifold 4 into the dephlegmator spray 33, and as it flows down through the pans it eondenses the heavy boiling point vapors and is preheated itself and the two flow down the dephlegmator leg at the bottom of which they are joined with the raw oil feed and the eondensed vapors which have been discharged into the bottom of the dephlegmator leg through pipe 31. The combined products, except the heavier ends taken of through line 6. then flow through line 24 to the heating tubes.

If it is desirable to make a closer regulation of the temperatures in the dephlegmator, the pressure distillate is directed from the tank lfi-into line 34 and pump 35 and discharged through line 36 controlled by valve 37 through manifold 53 into spray 38.

It will be appreciated that if the pressure distillate is allowed to flow down through the entire dephlegmator, all of it will be re-vaporized. Therefore, the pan 31 is so positioned that the temperature can be controlled and the distillate returned through the cracking tubes, thus by-passing the hotter vapors and the How of oil through the dephlegmator. The flow is sufliciently rapid through the line 32 to carry it to the cracking tubes before it vaporizes.

\Vhen using the dephlegmator for a heat interchanger and fractionating column simultaneously, and in order to get the highest efficiency,- often one interferes with the other. With this arrangement efficiencies can be maintained without effecting the operation of either or effecting the yield materially.

It will also be recognized that when an oil that has a considerable portion of low boiling point products is treated by the process explained, the lighter ends can be prevented from vaporizing in the dephlegmator and may be directed into the cracking tubes. Thus is obtained the maximum yield of low boiling point products therefrom.

In the same manner can be controlled the quality of distillates passing into the receiving tank.

It will be recognized that by thus controlling the flow of oil in the dephlegmator, that it may be subjected to a wide variation of temperature conditions and an oil that has a portion of low boiling point products in it can be treated and such products separated from the higher boiling point cuts while passing the latter to the cracking coils and the former to the pressure distillate tank.

By treating gas oil of approximately 32 Baum to temperatures ranging from 600 to 1000 F., and maintaining thereon pressures of from 25 to 250 pounds. a uniform quality distillate having a gravity of from 48 to 52 Baum and comprising approximately 40% to 60% of the charging stock is obtained.

I claim as my invention:

1. A process for cracking hydrocarbon oils, consisting in subjecting the hydrocarbon oil to cracking conditions of heat and pressure, in passing the evolved vapors to a dephlegmator, in maintaining a cycle of reflux condensate from the bottom of the dephlegmator through a cooling zone and back to an intermediate portion of the dephlegmator, such reflux condensate acting as a primary dephlegmating medium for the evolved vapors introduced to the dephlegmator, in continuously passing charging oil to the dephlegmator to initially contact with the vapors therein subsequent to the contact of the vapors with said reflux condensate and in maintaining a super-atmospheric pressure on the oil and vapors undergoing treatment.

2. A method of dephlegmating hydrocarbon oil vapors evolved from oil subjected to cracking conditions in a cracking process,

comprising introducing the vapors to a dephlegmating zone, apart from the zone .in

which the vapors were evolved from the oil,

and to which dephlegmating zone no unvaporized oil from the cracking process is admitted, in simultaneously introducing charging oil for the cracking process to said dephlegmating zone at a plurality of vertically disposed points thereof, in so controlling the passage of the oil introduced at one of said points through the dephlegmating zone that vaporization thereof is substantially prevented, in causing the oil introduced at another of the spaced points to physicall commingle with the hottest vapors in t e dephlegmating zone, and in returning portions of the unvaporized charging oil which has passed through said dephlegmating zone back tosaid dephlegmating zone at a point other than that at which such oil was originally introduced to said dephlegmating zone. 7

3. A method for dephlegmating hydrocarbon oil vapors which have been evolved from hydrocarbon oilsubjected to cracking conditions in a cracking process, which consists in introducing the vapors to a dephlegmating zone, in passing charging oil for the cracking process through a portion of such dephlegmating zone out of physical contact, with the vapors therein, in returning a portion of the oil which has passed through the 'dephlegmating zone out of contact with the vapors therein back into the dephlegmating zone, and in introducing the same thereto at spaced points in the travel of the vapors through the dephlegmatin zone,- whereby a portion of such oil will p ysically contact with the hottest vapors in the dephlegmating zone and a further portion of such oil will physically commingle with the coolest vapors in the dephlegmating column.

CARBON P. DUBBS. 

